The majority of the projects will use experimental preparations that require isolation and characterization of adult and neonatal cardiac muscle cells, or cardiocytes. This core will isolate cardiocytes from: 1) the adult cat, 2) the adult mouse, and 3) the neonatal rat. Adult cardiocytes will be isolated from both normal hearts and surgical models of pressure overload hypertrophy. Additionally, Project #4 will utilize mouse C2/C12 skeletal muscle cell lines. These demands will best be met by a Core Facility where supply purchases, reagent preparation, and routine procedures can be performed with an economy based on scale, with quality control monitored from a centralized, experienced authority, and time saved by providing labor-intensive services in a centralized facility.